Many large circulation periodicals are gathered on a binding line for stitching, trimming, bundling, and shipping. The binding line typically may include a plurality of signature feeding apparatus, each of which may have a driven rotary drum with a plurality of signature grippers disposed about the periphery thereof, and the signature grippers may be adapted to grip signatures seriatim as they are received from a signature supply means after they have been shifted therefrom to the rotary drum by cam driven suction means or other like components. Conventionally, the suction means will include oscillating suction grippers, together with a vacuum control valve.
In the case of saddle stitched books, a signature feeding apparatus will open the pages of a signature so that it may be dropped onto a saddle conveyor. The saddle conveyor then conveys that signature to the next signature feeding apparatus which may, in like manner, drop still another signature in straddle relation on top of the previously so distributed signature. In this manner, a book which is comprised of an entire collection of different signatures can be gathered for stitching on the saddle conveyor.
As will be appreciated by those skilled in the art, a book is simply a collection of signatures, regardless of the number of signatures and regardless of the manner in which the book is bound.
In more recent years, the books that are gathered on a binding line have been customized and/or personalized by utilizing a variety of different techniques. Typically, this involves computer control systems whereby different combinations of signature feeding apparatus along a binding line are selectively disabled and enabled in order to customize books according to demographics or the like. As a result, there has been a need to control operation of the various signature feeding apparatus on a binding line in a manner that is entirely satisfactory.
In the past, it will be appreciated that this has sometimes been accomplished in a variety of different ways, although almost always in a less than satisfactory manner. In this connection, experience has established that a desirable manner of shifting signatures seriatim from a signature supply hopper to a rotary drum is by means of oscillating suction grippers and, thus, one manner of disabling a signature feeding apparatus has been to shut off the vacuum by mounting an air cylinder on the vacuum valve which moves a sliding member across the vacuum inlet port leading to the oscillating suction grippers. While effective to disable the apparatus, this particular technique allows the oscillating suction grippers to continue impacting the stack of signatures in the supply hopper.
While the delivery of signatures is interrupted, the continual impacting of signatures is well know as being detrimental. Specifically, it has been found that, in practice, it is sometimes the case that, after a given signature feeding apparatus has been disabled for a period of time, a resumption of the vacuum will not cause the next signature in the signature supply hopper to be delivered to the rotary drum in such a manner that it can be gripped as intended by the signature grippers thereon. If this fails to occur, a signature that is needed for a given book will not be delivered to the saddle conveyor as required.
As a result, the book that was being formed will be defective and must be discarded and reordered. It is, of course, now known how to accomplish this objective as disclosed in various commonly owned patents and patent applications of R. R. Donnelley & Sons Company, but it would be highly desirable to further reduce, if not entirely eliminate, the waste that otherwise is known to exist by reason of this problem which is encountered when utilizing conventional disablement techniques. In other words, the binding line could be rendered more efficient by eliminating this known problem area.
In the past, this has been accomplished largely by utilizing what may be considered and described as mechanical "catch" systems. These systems are well suited for locking the suction grippers in a disabled position, but, in some instances, they require replacement after a certain period of operation. For this reason, it would be highly desirable to replace a mechanical system with a system requiring at least significantly reduced maintenance.
The present invention is directed to overcoming one or more of the foregoing problems and achieving one or more of the resulting objectives.